Carriage driving mechanism for typewriters or like machines



May 11, 1954 p RYAN 2,678,122

CARRIAGE DRIVING MECHANISM FOR TYPEWRITERS OR LIKE MACHINES Filed April29 1952 2 Sheets-Sheet l 7//////////A*llll INVENTOR Pgrtune PBganfla/PMP MW ATTORNEYS May 11, 1954 p RYAN 2,678,122

CARRIAGE DRIVING MECHANISM FOR TYPEWRITERS OR LIKE MACHINES Filed April29 1952 I 2 Sheets-Sheet 2 v INVENTOR Eartune PRyan BY my; w/fl fATTORNEYS Patented May ll, 1954 CARRIAGE DRIVING MECHANISM FORTYPEWRITERS OR LIKE MACHINES Fortune P. Ryan, New York, N. Y., assignorto Royal Typewriter Company, 1110., New York, N. Y., a corporation ofNew York Application April 29, 1952, Serial No. 284,983

14 Claims.

1 This invention relates to carriage driving mechanism for a typewriteror like machines and more particularly to means for varying the forcewith which a spring motor drives the machine carriage in the letterspacing direction and for indicating the loading of the spring motor.Many machines of the class referred to, e. g. typewriters, are equippedwith a carriage driving mechanism including a spring barrel connected tothe carriage by gearing or more commonly by a draw band wound around thebarrel and connected to the carriage. It is advantageous to be able toadjust the loading of the barrel spring either to compensate for changesin the spring characteristics due to age or use or to condition themechanism for most convenient and, agreeable use according to thepreference of individual operators, some operators preferring that thecarriage, which usually has to be returned manually, be urged in theletter spacing direction with greater or lesser force than otheroperators. A mechanism of this general character provided with means foradjusting the barrel spring is disclosed in the Hess and Myers Patent1,427,465 granted August 29, 1922.

In accordance with the present invention new and improved mechanism isprovided for adjusting the loading of the motor or barrel spring and forindicating the degree of loading of the spring to enable the operator tovisually determine the loading from a point generally above and in frontof the machine while simultaneously eiiecting the adjustment.

An object of the invention is to provide carriage driving mechanism ofthe character referred to including a spring barrel or motor andimproved mechanism for adjusting the loading of the spring.

Another object of the invention is to provide such mechanism which is soconstructed and arranged as to permit adjustment to be effected easilyby means of a finger piece or device located outside the machine frame.

Another object of the invention is to provide such a mechanism includinga novel arrangement of worm and worm wheel for adjusting the springtension or loading, the reactive force of the spring itself maintainingthe worm shaft against axial movement so as to dispense with thenecessity of providing plural thrust bearings for the worm shaft.

Another object of the invention is to provide a novel mechanism forindicating the loading of the spring and particularly in such a manneras to enable the spring loading indication to be viewed from above andin front of the machine.

Other objects of the invention will become apparent from a reading ofthe following description, the appended claims, and the accompanyingdrawings in which:

Figure 1 is a vertical sectional view, side to side of a typewriterembodying the invention, showing portions only of the machine frame andcarriage associated with carriage driving mechanism, some parts beingshown in elevation;

Figure 2 is a perspective view of a worm and shaft for adjusting thedriving mechanism drawn on a reduced scale;

Figure 3 is a perspective view of a shaft and worm wheel;

Figure 4 is a fragmentary vertical sectional view, fore and aft of themachine on the irregular line 4-4 of Figure 1 with some parts shown inelevation;

Figure 5 is a detail elevational view showing a spring anchor, spring,and shaft, as viewed when looking in the direction of the arrow !5 inFigure 4; and

Figure 6 is a fragmentary detail view partly in elevation and partly insection showing mechanism for operating an indicator to show theadjustment of the carriage driving mechanism.

Mechanism constructed in accordance with the invention is shown as beingembodied in a typewriter having a main frame A, equipped with asupporting bracket I for a lower track rail 2 carrying anti-frictionballs 3 which support a top rail 4 forming part of a carriage B, therails 2 and 4 and the balls 3 serving to mount the carriage B for letterspacing and return movements on the frame A.

A spring motor generally designated C is mounted on the frame A and isconnected to the carriage B for urging the carriage to move to the leftas viewed in Figure 1, i. e. in the letter spacing direction, under thecontrol of suitable feeding mechanism, e. g. an escapement mechanism(not shown). Generally considered, the spring motor 0 includes a barrel5 urged by a spring 6 to rotate counterclockwise in the direction of thearrow at in Figure 1. A draw band 'i wound around the barrel 5 has oneof its ends anchored as at 8 to the barrel and has its; other endequipped with a clip 9 which is fitted over an ear Ill on the carriage13. Thus, rotation of the barrel 5 in the direction of the arrow itwinds the i draw band I on the barrel and draws the carriage B in theletter spacing direction, that is to the left as viewed in Figure 1.

The motor C is carried by a bracket generally designated H secured byscrews 12 to the rear wall of the frame A. The bracket II is formed witha front plate I 3 and a rear plate I 4 which are apertured to providealigned bearings for a shaft I5 extending fore and aft of the machineand being rockably adjustable in the plate bearings. A spring anchor I6is secured to the shaft I5 by a set screw I1 and is positioned on theshaft so as to be disposed within and at the center of the barrel 5. Theanchor I3 is formed at its rear end with a sleeve part I 3 for mountingthe inner race I9 of a ball bearing assembly generally designated 20, anut 2I on the threaded outer end of the sleeve I8 holding the inner raceI9 securely on the anchor I6. Anti-friction balls 22 surrounding theinner race I9 are in turn surrounded by an outer bearing race 23 whichhas a snug fit, as for example a press fit, in the hub part 24 of a reardisc-like wall 25 of the barrel 5. In this way the barrel 5 is mountedcoaxially with the shaft I5 and so as to be rotatable about the shaft.The front disc-like wall 26 of the barrel is formed with a centralaperture 21 surrounding the front end of the spring anchor without,however, engaging the anchor. The barrel 5 may be equipped with a gear28 for operating ribbon spool driving mechanism (not shown).

The inner end of the coiled spring 3 is formed with a hook 29 whichengages a correspondingly shaped lug 33 on the spring anchor I6 forenabling the spring to be moved or loaded by rotating the shaft I5, andhence the spring anchor, counterclockwise as viewed in Figure 5. Theouter end of the spring is formed with a loop 3i fitted over a pin 32extending between the rear and front walls 25 and 26 of the barrel 5.When the mechanism is prepared for operation the spring 6 is tensionedor loaded and, since its inner end normally is held stationary by thespring anchor I6, the spring urges the barrel 5 to rotate in thedirection of the arrow a in Figure 1 for driving the carriage B in theletter spacing direction, as previously explained. When the carriage ismoved in the opposite or return direction, the barrel 5 is rotatedclockwise, as viewed in Figure 1, against the urge of the spring 6.

Mechanism is provided for conveniently adjusting the position of theanchor 16 angularly about the axis of the shaft I5 so as to vary theloading of the spring 6 and hence vary the force with which the carriageB is urged toward the left. In the form shown, a shaft 33 extendssideto-side of the machine through an aperture 34 in one side wall 35 ofthe frame A. The inner end of the shaft 33 is formed with a reducedportion 36 and a worm 3'! which meshes with a worm wheel 38 secured tothe spring adjusting shaft I5 by a set screw 33. The bracket I I has adepending part 49 provided at its end with a vertically disposed bearingpart 4I formed with an open top bearing recess 42 which receives thereduced part 36 of the shaft 33, the arrangement being such that theaperture 34 in the frame wall 35 and the bearing recess 42 journal theshaft 33 for rotation. The motor spring 6 reacts on the anchor I6, shaftI5 and worm wheel 38 so as to tend to turn the worm wheel 38 clockwise,that is in the direction of the arrow 1) in Figure 1, in consequence ofwhich the worm wheel 38 tends to force or thrust the worm 31 and shaft33 toward the left. This thrust is resisted by engagement of the leftend 3'1 of the worm 31 with the right face 4I of the vertical bearingpart M on the bracket II. By this arrangement a single thrust bearingprovided by the parts 37 and 4M serves, with the cooperation of thespring 6, anchor l6, shaft I5 and worm wheel 38, to maintaincorresponding extent.

4 the shaft 33 against axial movement Without the necessity of providingplural accurately machined or positioned thrust bearings. A fingerpiece, as shown a knurled knob 43, secured to the shaft 33 by a screw 43provides for easy manual turning of the shaft 33.

In order to vary the loading of the spring 6 and hence the force withwhich the carriage B is urged in the letter spacing direction, theknurled knob 43 and shaft 33 are turned so as to cause the worm 31 torotate the worm wheel 38, shaft I5 and spring anchor I6 clockwise asviewed from the front if the spring loading is to be increased, orcounterclockwise if the spring loading is to be decreased.

Mechanism is provided for indicating the degree of loading of the spring5. As shown, an indexed indicator member or dial, generally designated44, is journaled for limited rotation on the bearing part 45 of a screw46 carried by the upper part of the front bracket plate l3, a spacer 4'?being interposed between the bracket plate I3 and the dial 44. The dial44 is formed with two sectors, one sector 48 comprising an arcuateindexed portion and being of relatively large radius, and the othersector 49 being of relatively small radius. The sector 48 has a bevelledperipheral face, the longer radius edge of this sector being disposedtoward the rear of the shorter radius edge as shown in Figure 4. Thesector or portion 49 is arcuately toothed and meshes with the teeth ofthe worm wheel 38 so that when the worm wheel is rotated for adjustingthe spring tension the indicator dial 44 will be rotated a The Wormwheel 38 has relatively wide teeth for smooth and proper cooperationwith the worm 3i, and these teeth have a circumferential lead or slantas is characteristic of conventional worm Wheel teeth. In order toenable the teeth of the dial sector 43 to cooperate properly with theteeth of the worm Wheel 38 without binding, the teeth of the sector 49are formed so as to be relatively narrow as compared to the teeth of theworm wheel 38.

Because of the difference in the length of the radii of the sectors 48and 49, shoulders 50 and 5| are provided at the peripheral meetin pointsof the sectors. These shoulders are engageable respectively with theworm wheel 38 for limiting th permitted rotation of the dial 44 and wormWheel 38 and for thus limiting the extent to which the spring anchor Itcan be turned for adjusting the loading of the spring 6.

All of the mechanism for adjusting the spring 6 and for'operating theindicator, with the exception of the topmost part of the dial 44, iscovered by a top plate or masking part 52 secured to the frame A byscrews 53. The plate 52 is formed with an opening 54 behind the carriageB sufficiently large to permit the top part of the dial 44 to projectslightly above the plate 52 so that it may easily be viewed from aposition above and in front of the dial, thus enabling the operator toobserve the indicator dial from a position generally in front of themachine and while ad justing the mechanism by turning the knob 43. Partof the plate 52 immediately in front of the openin 54 is depressed asshown at 55 so as to provide a pointer adapted to be viewed inconnection with the indicia or numerals on the dial 44.

The mechanism disclosed embodies th invention in its preferred form, butit is intended that the disclosure be illustrative rather thandefinitive of the invention, the invention being defined in the appendedclaims.

I claim:

1. In a typewriter or like machine, a frame having a masking part withan Opening therein; a carriag mounted for letter spacing and returntravel on said frame; a spring motor mounted on said frame; drivingconnections between said motor and said carriage; means for adjustingsaid motor to vary its driving effect onsaid carriage, said adjustingmeans being substantially enclosed and hidden by said frame; a memberconnected to said adjusting means and projecting through a wall of saidframe; a manually operable finger piece on said member outside said wallfor operating said member from a location outside said wall to operatethe frame enclosed adjustin mechanism; a device bearing indicia forindicating the adjustment of said motor;

means mounting said device so as substantially to a be hidden by saidmasking part but in such relation to said opening in said masking partas to enable a portion only of said device to be observed from outsidesaid frame and said masking part; and means covered by said masking partfor drivingly connecting said adjusting means to said device.

2. In a typewriter or like machine, a frame; a carriage mounted forletter spacing and return travel on said frame; a spring motor mountedon said frame; driving connections between said motor and said carriage;means for adjusting said motor to vary its driving effect on saidcarriage, said adjusting means being substantially enclosed and hiddenby said frame; a member connected to said adjusting means and projectingthrough a wall of said frame; a manually operable finger piece on saidmember outside said wall for operating said member from a locationoutside said wall to operate the fram enclosed adjusting mechanism; adevice bearing indicia for indicating the adjustment of said motor;means mounting said device in a position enabling it to be observed fromoutside said frame; and means enclosed and hidden by said frame fordrivingly connecting said adjusting means to said device.

3. In a typewriter or like machine, a frame; a carriage mounted forletter spacing and return travel on said frame; a spring motor mountedon said frame; driving connections between said motor and said carriage;means for adjusting said motor to vary its driving effect on saidcarriage, said adjustin means being substantially enclosed and hidden bysaid frame; a member connected to said adjusting means and projectingthrough a wall of said frame; a manually operable finger piece on saidmember outside said wall for operating said member from a locationoutside said wall to operat the frame enclosed adjusting mechanism; adevice bearing indicia for indicating the adjustment of said motor;means mounting said device on said frame so as to be substantiallyenclosed and hidden by said frame; an opening in said frame throughwhich a part only of said device extends to enable it to be observedfrom outside said frame; and means enclosed and hidden by said frame fordrivingly connecting said adjusting means to said device.

4. In mechanism for driving the travelling carriage of a typewriter orlike machine, a frame; a shaft journalled on said frame for rotaryadjustment; a barrel mounted for rotation coaxially with said shaft andhaving means for drivingly 6 connectin said barrel to said carriage; acoiled spring connected at its opposite ends to said shaft and saidbarrel respectively and being adapted when loaded to urge said barrel torotate in a predetermined direction; means for rotating said shaft forvariably loading said spring comprising a worm wheel fixed to saidshaft, and a rotatable worm cperatively engaging said worm wheel andbeing provided with means, for rotating said worm; and means forindicating the adjustment of said shaft and hence the loading of saidspring comprising an indexed indicator device and a toothed partdrivingly connected to said device and meshing with said worm wheel.

5. In mechanism for driving the travelling carriage of a typewriter orlike machine, a frame; a shaft journalled on said frame for rotaryadjustment; a barrel mounted for rotation coaxially with said shaft andhaving means for drivingly connecting said barrel to said carriage; acoiled spring connected at its opposite ends to said shaft and saidbarrel respectively and being adapted when loaded to urge said barrel torotate in a predetermined direction; means for rotating said shaft forvariably loading said spring comprising a worm wheel fixed to said shaftand having teeth which are relatively wide in a direction parallel tosaid shaft, and a rotatable worm cperatively engaging said worm wheeland being provided with means for rotating said worm; and means forindicating the adjustment of said shaft and hence the loading of saidspring comprising a rotatable indicator member having an indexed portionand an arcuate portion formed with relatively narrow teeth, and meansmounting said indicator menu her for rotation about an axis parallel tothe axis of said shaft and with the relatively narrow teeth of saidindicator member meshing with the relatively wide teeth of said wormwheel.

6. In a'typewriter or like machine, a frame structure; a carriagemounted thereon for letter spacing and return travel from side to sideof the machine; a shaft journalled for rotary adjustment on a rear partof said frame structure and extending fore and aft of said machine andbelow the top of said frame structure, a rear top part of said framestructure covering said shaft; a barrel mounted for rotation coaxially'with said shaft and having means for drivingly connecting said barrel tosaid carriage; a coiled spring connected at its opposite ends to saidshaft and said barrel respectively and being adapted when loaded to urgesaid barrel to rotate in a predetermined direction; adjusting meansmounted under and covered by said frame structure rear top part forrotating said shaft for variably loading said spring; an opening in saidframe structure rear top part; and means for indicating the adjustmentof said shaft and hence the loading of said spring comprising an indexedmember, means mounting said member so that a part of said member andsaid mounting means therefor are covered by said frame structure reartop part and another part of said member is so positioned with respectto said opening as to be viewable from above said machine, and meansdrivingly connecting said member to said shaft.

'7. In a typewriter or like machine, a frame structure; a carriagemounted thereon for letter spacing and return travel from side to sideof. the machine; a shaft journalled for rotary adjustment on a rear partof said frame structure and extending fore and aft of said machine andbelow the top of said frame structure, a rear top part of said framestructure covering said shaft; a barrel mounted for rotation coaxiallywith said shaft and having means for drivingly connecting said barrel tosaidcarriage; a coiled spring connected at its opposite ends to saidshaft and said barrel respectively and being adapted when loaded to urgesaid barrel to rotate in a predetermined direction; adjusting meansmounted under and covered by said frame structure rear top part forrotating said shaft for variably loading said spring and comprising aworm wheel fixed to said shaft, and a rotatable worm operativelyengaging said Worm wheel and being provided with means for rotating saidworm; an opening in said frame structure rear top part; and means forindicating the adjustment of said shaft and hence the loading of saidspring comprising an indexed member, means mounting said member so thata part of said member and said mounting means therefor are covered bysaid frame structure rear top part and another part of said member is sopositioned with respect to said opening as to be viewable from abovesaid machine, and an arcuate toothed part underneath said framestructure top part and being fast with said indexed member and meshingwith saidworm wheel.

8. In a typewriter or like machine, a frame structure; a carriagemounted thereon for letter spacing and return travel from side to sideof the machine; a shaft journalled for rotary adjustment on a rear partof said frame structure and extending fore and aft of said machine andbelow'the top of said frame structure, a rear top part of said framestructure covering said shaft; a barrel mounted for rotation coaxiallywith said shaftand having means for drivingly connecting said barrel tosaid carriage; a coiled spring connected at its opposite ends to saidshaft and said barrel respectively and being adapted when loaded to urgesaid barrel to rotate in a, predetermined direction; adjusting meansmounted under and covered by said frame structure rear top part forrotating said shaft for variably loading said spring and comprising aworm wheel fixed to said shaft, and a rotatable worm operativelyengaging said worm wheel and being provided with means for rotating saidworm; an opening in said frame structure rear top part; and means forindicating the adjustment of said shaft and hence the loading of saidspring comprising'an indexed member having an arcuate part formed with abevelled peripheral face bearing indicia, means mounting said in dexedmember for rotation about an axis parallel.

to said shaft and below said frame structure rear top part with theupper portion of said.

arcuate part of said member projecting partially through said openingand with the longer radius edgeof said bevelled peripheral face behindthe shorter radius edge thereof, whereby the indicia on said peripheralface may be read from a viewing point above and in front of saidopening, and a toothed sector on said indexed member meshing with saidworm wheel.

9. In a typewriter or like machine, a frame structure; a carriagemounted thereon for letter spacing and return travel from side to sideof the machine; a first shaft journalled for rotary adjustment on a rearpart of said frame structure and extending fore and aft of said machineand below the top of said frame structure, a rear top part of said framestructure covering said shaft; a barrel mounted for rotation coaxiallywith said shaft and having means for drivingly connecting said barreltosaid carriage; a coiled spring connected at its opposite ends to saidshaft and said barrel respectively and being adapted when loaded to urgesaid barrel to rotate in a predetermined direction; adjusting meansmounted under and covered by said frame structure rear top part forrotating said shaft for variably loading said spring and comprising aworm wheel fixed to said shaft, a worm operatively engaging said Wormwheel and being rotatable about an axis extending from side to side ofthe machine, a worm shaft fast with said worm and projecting through andoutwardly beyond a side wall of said frame structure, and a finger pieceon the outer end of said worm shaft outside said side wall; an openingin said frame structure rear top part; and means for indicating theadjustment of said first shaft and hence the loading of said springcomprising an indexed member having an arcuate part formed with abevelled peripheral face bearing indicia, means mounting said indexedmember for rotation about an axis parallel to said first shaft and belowsaid frame structure rear top part with the upper portion of saidarcuate part of said member projecting partially through said openingand with the longer radius edge of said bevelled peripheral face behindthe shorter radius edge thereof, whereby the indicia on said peripheralface may be read from a viewing point above and in front of saidopening, and a toothed sector on said indexed member meshing with saidworm wheel.

10, In mechanism for driving the travelling carriage of a typewriter orlike machine, a frame; a shaft journalled on said frame for rotaryadjustment; a barrel mounted for rotation coaxially with said shaft andhaving means for drivingly connecting said barrel to said carriage; acoiled spring connected at its opposite ends to said shaft and saidbarrel respectively and being adapted when loaded to urge said barrel torotate in a predetermined direction; means for rotating said shaft forvariably loading said spring comprising a worm wheel fixed to saidshaft, and a rotatable worm operatively engaging said worm wheel andbeing provided with means for rotating said Worm; and means forindicating the adjustment of said shaft and hence the loading of saidspring comprising a rotatable indicator member having an indicia bearingsector of relatively long radius and a toothed sector of relativelyshort radius, the difference in the radii of said sectors providingsubstantially radial shoulders at the peripheral meeting points of saidSeetors, and means mounting said indicator member for rotation about anaxis parallel to the axis of said shaft and with the toothed sector ofsaid indicator member meshing with said worm Wheel, said shoulders beingrespectively engageable with said worm wheel to determine the limits ofmovement of said indicator member and said Worm wheel and said shaft tothereby determine the limits of variation of loading of said spring.

11. In mechanism for driving the travelling carriage of a typewriter orlike machine, a frame; a shaft journalled on said frame for rotaryadjustment; a barrel mounted for rotation coaxially with said shaft andhaving means for drivingly connecting said barrel to said carriage; acoiled spring connected at its opposite ends to said shaft and saidbarrel respectively and being adapted when loaded to urge said barrel torotate in a predetermined direction; means for rotating said shaft forvariably loading saidspring comprising a worm wheel fixed to said shaftand having teeth which are relatively wide in a direction parallel tosaid shaft, and a rotatable worm operatively engaging said worm wheeland being provided with means for rotating said worm; and means forindicating the adjustment of said shaft and hence the loading of saidspring comprising a rotatable indicator member having an indicia bearingsector of relatively long radius and a toothed sector of relativelyshort radius, the teeth of said toothed sector being relatively narrowand the difference in the radii of said sectors providing substantiallyradial shoulders at the peripheral meeting points of said sectors, andmeans mounting said indicator member for rotation about an axis parallelto the axis of said shaft and with the toothed sector of said indicatormember meshing with said worm Wheel, said shoulders being respectivelyengageable with said worm wheel to determine the limits of movement ofsaid indicator member and said worm a shaft journalled on said frame forrotary adjustment; a barrel mounted for rotation coaxially with saidshaft and having means for drivingly connecting said barrel to saidcarriage; a coiled spring connected at its opposite ends to said shaftand said barrel respectively and being adapted when loaded to urge saidbarrel to rotate in a predetermined direction and to urge said shaftreactively to rotate in the opposite direction; a worm wheel fixedtosaid shaft; a worm meshing with said worm wheel and being subjectedthereby to axial thrust force due to the reactive urge of said spring; aworm shaft fast with said worm; means including a single fixed thrustbearing part and a single cooperating thrust bearing part on said wormshaft for journalling said worm shaft and for holding it and said wormagainst axial movement by said thrust force, said thrust force being duesolely to the loading of said spring and constantly holding the thrustbearing part on said worm shaft snugly against said fixed thrust bearingpart; and a rotatable indicator member having an indicia bearing sectorand a toothed sector meshing with said worm wheel.

13. In mechanism for driving the travelling carriage of a typewriter orlike machine, a frame; a first shaft journalled on said frame. forrotary adjustment; a barrel mounted for rotation coaxially with saidshaft and having means for drivingly connecting said barrel to saidcarriage; a coiled spring connected at its opposite ends to said shaftand said barrel respectively and being adapted when loaded to urge saidbarrel to rotate in a predetermined direction and to urge said shaftreactively to rotate in the opposite direction; a worm wheel fixed tosaid shaft; a worm meshing with said worm wheel and being subjectedthereby to axial thrust force due to the reactive urge of said spring; aworm shaft fast with said worm; means including a single fixed thrustbearing part and a single cooperating l. lel to the axis of thrustbearing part on said worm shaft for journalling said worm shaft and forholding it and said worm against axial movement by said thrust force,said thrust force being due solely to the loading of said spring andconstantly holding the thrust bearing part on said worm shaft snuglyagainst said fixed thrust bearing part; a rotatable indicator memberhaving an indicia bearing sector of relatively long radius and a toothedsector of relatively short radius, the difference in the radii of saidsectors providing radial shoulders at the peripheral meeting points ofsaid sectors; and means mounting said indicator member for rotationabout an axis paralsaid first shaft and with the toothed sector of saidindicator member meshing with said worm wheel, said shoulders beingrespectively engageable with said worm wheel to determine the limits ofmovement of said indicator member and said worm wheel to thereby limitthe range of adjustment of said first shaft, and consequently todetermine the limits of variation of loading of said spring.

14. In a typewriter or like machine, a frame structure; a carriagemounted thereon for letter spacing and return travel from side to sideof the machine; a shaft journalled for rotary adjustment on a rear partof said frame structure and extending fore and aft of said machine andbelow the top of said frame structure, a rear top part of said framestructure covering said shaft; a barrel mounted for rotation coaxiallywith said shaft and having means for drivingly connecting said barrel tosaid carriage; a coiled spring connected at its opposite ends to saidshaft and said barrel respectively and being adapted when loaded to urgesaid barrel to rotate in a predetermined direction; adjusting meansmounted under and covered by said frame structure rear top part forrotating said shaft for variably loading said spring; an opening in saidframe structure rear top part; and means for indicating the adjustmentof said shaft and hence the loading of said spring comprising an indexedmember having an arcuate part formed with a bevelled peripheral facebearing indicia, means mounting said indexed member for rotation aboutan axis parallel to said shaft and below said frame structure rear toppart with the upper portion of said arcuate part of said mem berprojecting partially through said opening and with the longer radiusedge of said bevelled peripheral face behind the shorter radius edgethereof, whereby the indicia on said peripheral face may be read from aviewing point above and in front of said opening, and means drivinglyconnecting said indexed member to said shaft.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 596,371 Jenne Dec. 28, 1897 1,427,465 Hess et a1 Aug. 29, 1922

